﻿

#ifndef __SHA1_H_
#define __SHA1_H_
////////////////////////////////////////////////////////////////////////////////
#ifndef _SHA_enum_
#define _SHA_enum_
enum
{
    shaSuccess = 0,
    shaNull, /* Null pointer parameter */
    shaInputTooLong, /* input data too long */
    shaStateError/* called Input after Result */
};
#endif
#define SHA1HashSize 20
////////////////////////////////////////////////////////////////////////////////
typedef struct SHA1Context
{
    unsigned int Intermediate_Hash[SHA1HashSize/4]; /* Message Digest */
    unsigned int Length_Low; /* Message length in bits */
    unsigned int Length_High; /* Message length in bits */
    /* Index into message block array */
    unsigned int Message_Block_Index;
    unsigned char Message_Block[64]; /* 512-bit message blocks */
    int Computed; /* Is the digest computed? */
    int Corrupted; /* Is the message digest corrupted? */
} SHA1Context;
////////////////////////////////////////////////////////////////////////////////
/* 
* Define the SHA1 circular left shift macro 
*/
#define SHA1CircularShift(bits,word) (((word) << (bits)) | ((word) >> (32-(bits))))
/* Local Function Prototyptes */
static void SHA1PadMessage(SHA1Context*);
static void SHA1ProcessMessageBlock(SHA1Context*);
////////////////////////////////////////////////////////////////////////////////
/* 
* SHA1Reset 
* 
* Description: 
* This function will initialize the SHA1Context in preparation 
* for computing a new SHA1 message digest. 
* 
* Parameters: 
* context: [in/out] 
* The context to reset. 
* 
* Returns: 
* sha Error Code. 
* 
*/
////////////////////////////////////////////////////////////////////////////////
inline int SHA1Reset(SHA1Context *context) { //初始化状态
    if (!context){
        return shaNull;
    }
    context->Length_Low = 0;
    context->Length_High = 0;
    context->Message_Block_Index = 0;
    context->Intermediate_Hash[0] = 0x67452301;//取得的HASH结果（中间数据）
    context->Intermediate_Hash[1] = 0xEFCDAB89;
    context->Intermediate_Hash[2] = 0x98BADCFE;
    context->Intermediate_Hash[3] = 0x10325476;
    context->Intermediate_Hash[4] = 0xC3D2E1F0;
    context->Computed = 0;
    context->Corrupted = 0;
    return shaSuccess;
}
////////////////////////////////////////////////////////////////////////////////
/* 
* SHA1Result 
* 
* Description: 
* This function will return the 160-bit message digest into the 
* Message_Digest array provided by the caller. 
* NOTE: The first octet of hash is stored in the 0th element, 
* the last octet of hash in the 19th element. 
* 
* Parameters: 
* context: [in/out] 
* The context to use to calculate the SHA-1 hash. 
* Message_Digest: [out] 
* Where the digest is returned. 
* 
* Returns: 
* sha Error Code. 
* 
.*/
////////////////////////////////////////////////////////////////////////////////
inline int SHA1Result(SHA1Context *context,unsigned char Message_Digest[SHA1HashSize]){
    int i;
    if (!context || !Message_Digest){
        return shaNull;
    }
    if (context->Corrupted){
        return context->Corrupted;
    }
    if (!context->Computed){
        SHA1PadMessage(context);
        for(i=0; i<64; ++i){
            /* message may be sensitive, clear it out */
            context->Message_Block[i] = 0;
        }
        context->Length_Low = 0; /* and clear length */
        context->Length_High = 0;
        context->Computed = 1;
    }
    for(i = 0; i < SHA1HashSize; ++i){
        Message_Digest[i] = context->Intermediate_Hash[i>>2]
        >> 8 * ( 3 - ( i & 0x03 ) );
    }
    return shaSuccess;
}
////////////////////////////////////////////////////////////////////////////////
/* 
* SHA1Input 
* 
* Description: 
* This function accepts an array of octets as the next portion 
* of the message. 
* 
* Parameters: 
* context: [in/out] 
* The SHA context to update 
* message_array: [in] 
* An array of characters representing the next portion of 
* the message. 
* length: [in] 
* The length of the message in message_array 
* 
* Returns: 
* sha Error Code. 
* 
*/
////////////////////////////////////////////////////////////////////////////////
inline int SHA1Input(SHA1Context *context,const unsigned char *message_array,unsigned length){
    if (!length){
        return shaSuccess;
    }
    if (!context || !message_array){
        return shaNull;
    }
    if (context->Computed){
        context->Corrupted = shaStateError;
        return shaStateError;
    }
    if (context->Corrupted){
        return context->Corrupted;
    }
    while(length-- && !context->Corrupted){
        context->Message_Block[context->Message_Block_Index++] =
            (*message_array & 0xFF);
        context->Length_Low += 8;
        if (context->Length_Low == 0){
            context->Length_High++;
            if (context->Length_High == 0){
                /* Message is too long */
                context->Corrupted = 1;
            }
        }
        if (context->Message_Block_Index == 64){
            SHA1ProcessMessageBlock(context);
        }
        message_array++;
    }
    return shaSuccess;
}
////////////////////////////////////////////////////////////////////////////////
/* 
* SHA1ProcessMessageBlock 
* 
* Description: 
* This function will process the next 512 bits of the message 
* stored in the Message_Block array. 
* 
* Parameters: 
* None. 
* 
* Returns: 
* Nothing. 
* 
* Comments: 
* Many of the variable names in this code, especially the 
* single character names, were used because those were the 
* names used in the publication. 
* 
*/
////////////////////////////////////////////////////////////////////////////////
static void SHA1ProcessMessageBlock(SHA1Context *context){
    const unsigned int K[] = { /* Constants defined in SHA-1 */
        0x5A827999,
        0x6ED9EBA1,
        0x8F1BBCDC,
        0xCA62C1D6
    };
    int t; /* Loop counter */
    unsigned int temp; /* Temporary word value */
    unsigned int W[80]; /* Word sequence */
    unsigned int A, B, C, D, E; /* Word buffers */
    /* 
    * Initialize the first 16 words in the array W 
    */
    for(t = 0; t < 16; t++){
        W[t] = context->Message_Block[t * 4] << 24;
        W[t] |= context->Message_Block[t * 4 + 1] << 16;
        W[t] |= context->Message_Block[t * 4 + 2] << 8;
        W[t] |= context->Message_Block[t * 4 + 3];
    }
    for(t = 16; t < 80; t++){
        W[t] = SHA1CircularShift(1,W[t-3] ^ W[t-8] ^ W[t-14] ^ W[t-16]);
    }
    A = context->Intermediate_Hash[0];
    B = context->Intermediate_Hash[1];
    C = context->Intermediate_Hash[2];
    D = context->Intermediate_Hash[3];
    E = context->Intermediate_Hash[4];
    for(t = 0; t < 20; t++){
        temp = SHA1CircularShift(5,A) +
            ((B & C) | ((~B) & D)) + E + W[t] + K[0];
        E = D;
        D = C;
        C = SHA1CircularShift(30,B);
        B = A;
        A = temp;
    }
    for(t = 20; t < 40; t++){
        temp = SHA1CircularShift(5,A) + (B ^ C ^ D) + E + W[t] + K[1];
        E = D;
        D = C;
        C = SHA1CircularShift(30,B);
        B = A;
        A = temp;
    }
    for(t = 40; t < 60; t++){
        temp = SHA1CircularShift(5,A) +
            ((B & C) | (B & D) | (C & D)) + E + W[t] + K[2];
        E = D;
        D = C;
        C = SHA1CircularShift(30,B);
        B = A;
        A = temp;
    }
    for(t = 60; t < 80; t++){
        temp = SHA1CircularShift(5,A) + (B ^ C ^ D) + E + W[t] + K[3];
        E = D;
        D = C;
        C = SHA1CircularShift(30,B);
        B = A;
        A = temp;
    }
    context->Intermediate_Hash[0] += A;
    context->Intermediate_Hash[1] += B;
    context->Intermediate_Hash[2] += C;
    context->Intermediate_Hash[3] += D;
    context->Intermediate_Hash[4] += E;
    context->Message_Block_Index = 0;
}
////////////////////////////////////////////////////////////////////////////////
/* 
* SHA1PadMessage 
* 
* Description: 
* According to the standard, the message must be padded to an even 
* 512 bits. The first padding bit must be a ’1’. The last 64 
* bits represent the length of the original message. All bits in 
* between should be 0. This function will pad the message 
* according to those rules by filling the Message_Block array 
* accordingly. It will also call the ProcessMessageBlock function 
* provided appropriately. When it returns, it can be assumed that 
* the message digest has been computed. 
* 
* Parameters: 
* context: [in/out] 
* The context to pad 
* ProcessMessageBlock: [in] 
* The appropriate SHA*ProcessMessageBlock function 
* Returns: 
* Nothing. 
* 
*/
////////////////////////////////////////////////////////////////////////////////
static void SHA1PadMessage(SHA1Context *context){
    /* 
    * Check to see if the current message block is too small to hold 
    * the initial padding bits and length. If so, we will pad the 
    * block, process it, and then continue padding into a second 
    * block. 
    */
    if (context->Message_Block_Index > 55){
        context->Message_Block[context->Message_Block_Index++] = 0x80;
        while(context->Message_Block_Index < 64){
            context->Message_Block[context->Message_Block_Index++] = 0;
        }
        SHA1ProcessMessageBlock(context);
        while(context->Message_Block_Index < 56){
            context->Message_Block[context->Message_Block_Index++] = 0;
        }
    } else {
        context->Message_Block[context->Message_Block_Index++] = 0x80;
        while(context->Message_Block_Index < 56){
            context->Message_Block[context->Message_Block_Index++] = 0;
        }
    }
    /* 
    * Store the message length as the last 8 octets 
    */
    context->Message_Block[56] = context->Length_High >> 24;
    context->Message_Block[57] = context->Length_High >> 16;
    context->Message_Block[58] = context->Length_High >> 8;
    context->Message_Block[59] = context->Length_High;
    context->Message_Block[60] = context->Length_Low >> 24;
    context->Message_Block[61] = context->Length_Low >> 16;
    context->Message_Block[62] = context->Length_Low >> 8;
    context->Message_Block[63] = context->Length_Low;
    SHA1ProcessMessageBlock(context);
}
////////////////////////////////////////////////////////////////////////////////
#endif //_SHA1_H_
